The first council of Dvin, in 506, accepted the Henotikon, the imperial formula of union that avoided the language of Chalcedon rather than confronting it, and at that point the Armenian position was one held by a great many eastern Christians. The second, traditionally dated to 554 or 555, went further, condemning the teaching associated with Nestorius and rejecting the Definition of Chalcedon outright, and it introduced the distinct Armenian era of reckoning that dates from 552. The third, at the beginning of the seventh century, ended communion with the Georgian Church, whose catholicos Kirion had aligned himself with Constantinople, and that break has never been healed. The effect of the three together was to place the Armenian Church among the non-Chalcedonian or Oriental Orthodox communions, alongside the Copts, the Syriac Orthodox and the Ethiopians.
Whether the difference between the Armenian formula and the Chalcedonian one was ever a difference about Christ, rather than about the Greek words for nature and person and about who was entitled to impose them, has been argued for fifteen hundred years. A series of joint declarations signed since the 1970s state that the two sides profess the same faith in different terms while remaining separate churches, which is an agreement about language and not yet about communion.